1. Field of the Invention
This invention relates to a process for the low polymerization of isobutene using a solid acid catalyst, in particular, high silica mordenite catalyst with a specified solid acid quantity, and more particularly, it is concerned with a process for the selective low polymerization of only isobutene in an isobutene-containing hydrocarbon mixture.
2. Description of the Prior Art
In the low polymerization of isobutene in a hydrocarbon mixture containing isobutene, it is well known to contact the hydrocarbon mixture with a solid acid catalyst such as silica.alumina, zeolite or cation exchange resin. This method is used for the removal of isobutene in C.sub.4 hydrocarbon mixtures.
For example, there have hitherto been proposed (1) a method comprising contacting a C.sub.4 hydrocarbon mixture with an isomerization catalyst such as palladium, platinum or nickel to isomerize 1-butene in 2-butene, further contacting with a solid acid catalyst such as activated clay or silica.alumina to low-polymerize isobutene and separating the resulting low polymers (Japanese Patent Application OPI (Kokai) No. 8201/1976), (2) a method comprising contacting a C.sub.4 hydrocarbon mixture with a crystalline molecular sieve (10X Molecular Sieve) having effective pores of about 8 to 8.2 .ANG. to remove isobutene (Japanese Patent Publication No. 42803/1972), (3) a method comprising contacting a C.sub.4 hydrocarbon mixture with a synthetic zeolite (ZSM-4) to low-polymerize selectively isobutene (Japanese Patent Publication No. 29121/1976) and (4) a method comprising feeding a C.sub.4 hydrocarbon mixture to a distilling column packed with a cation exchange resin, low-polymerizing isobutene and separating and removing the low polymers from the bottom thereof (U.S. Pat. No. 4,215,011).
However, any of these methods is not suitable as a method of producing 1-butene free from isobutene since 1-butene contained in the C.sub.4 hydrocarbon mixture tends to be isomerized in 2-butene.